src/sync.c

   1 /* sync - update the super block
   2    Copyright (C) 1994-2024 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Jim Meyering */
  18
  19 #include <config.h>
  20 #include <getopt.h>
  21 #include <stdio.h>
  22 #include <sys/types.h>
  23
  24 #include "system.h"
  25
  26 /* The official name of this program (e.g., no 'g' prefix).  */
  27 #define PROGRAM_NAME "sync"
  28
  29 #define AUTHORS                                 \
  30   proper_name ("Jim Meyering"),                 \
  31   proper_name ("Giuseppe Scrivano")
  32
  33 #ifndef HAVE_SYNCFS
  34 # define HAVE_SYNCFS 0
  35 #endif
  36
  37 enum sync_mode
  38 {
  39   MODE_FILE,
  40   MODE_DATA,
  41   MODE_FILE_SYSTEM,
  42   MODE_SYNC
  43 };
  44
  45 static struct option const long_options[] =
  46 {
  47   {"data", no_argument, nullptr, 'd'},
  48   {"file-system", no_argument, nullptr, 'f'},
  49   {GETOPT_HELP_OPTION_DECL},
  50   {GETOPT_VERSION_OPTION_DECL},
  51   {nullptr, 0, nullptr, 0}
  52 };
  53
  54 void
  55 usage (int status)
  56 {
  57   if (status != EXIT_SUCCESS)
  58     emit_try_help ();
  59   else
  60     {
  61       printf (_("Usage: %s [OPTION] [FILE]...\n"), program_name);
  62       fputs (_("\
  63 Synchronize cached writes to persistent storage\n\
  64 \n\
  65 If one or more files are specified, sync only them,\n\
  66 or their containing file systems.\n\
  67 \n\
  68 "), stdout);
  69
  70       fputs (_("\
  71   -d, --data             sync only file data, no unneeded metadata\n\
  72 "), stdout);
  73       fputs (_("\
  74   -f, --file-system      sync the file systems that contain the files\n\
  75 "), stdout);
  76
  77       fputs (HELP_OPTION_DESCRIPTION, stdout);
  78       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  79       emit_ancillary_info (PROGRAM_NAME);
  80     }
  81   exit (status);
  82 }
  83
  84 /* Sync the specified FILE, or file systems associated with FILE.
  85    Return 1 on success.  */
  86
  87 static bool
  88 sync_arg (enum sync_mode mode, char const *file)
  89 {
  90   bool ret = true;
  91   int open_flags = O_RDONLY | O_NONBLOCK;
  92   int fd;
  93
  94 #if defined _AIX || defined __CYGWIN__
  95   /* AIX 7.1, CYGWIN 2.9.0, fsync requires write access to file.  */
  96   if (mode == MODE_FILE)
  97     open_flags = O_WRONLY | O_NONBLOCK;
  98 #endif
  99
 100   /* Note O_PATH might be supported with syncfs(),
 101      though as of Linux 3.18 is not.  */
 102   fd = open (file, open_flags);
 103   if (fd < 0)
 104     {
 105       /* Use the O_RDONLY errno, which is significant
 106          with directories for example.  */
 107       int rd_errno = errno;
 108       if (open_flags != (O_WRONLY | O_NONBLOCK))
 109         fd = open (file, O_WRONLY | O_NONBLOCK);
 110       if (fd < 0)
 111         {
 112           error (0, rd_errno, _("error opening %s"), quoteaf (file));
 113           return false;
 114         }
 115     }
 116
 117   /* We used O_NONBLOCK above to not hang with fifos,
 118      so reset that here.  */
 119   int fdflags = fcntl (fd, F_GETFL);
 120   if (fdflags == -1
 121       || fcntl (fd, F_SETFL, fdflags & ~O_NONBLOCK) < 0)
 122     {
 123       error (0, errno, _("couldn't reset non-blocking mode %s"),
 124              quoteaf (file));
 125       ret = false;
 126     }
 127
 128   if (ret == true)
 129     {
 130       int sync_status = -1;
 131
 132       switch (mode)
 133         {
 134         case MODE_DATA:
 135           sync_status = fdatasync (fd);
 136           break;
 137
 138         case MODE_FILE:
 139           sync_status = fsync (fd);
 140           break;
 141
 142 #if HAVE_SYNCFS
 143         case MODE_FILE_SYSTEM:
 144           sync_status = syncfs (fd);
 145           break;
 146 #endif
 147
 148         default:
 149           unreachable ();
 150         }
 151
 152       if (sync_status < 0)
 153         {
 154           error (0, errno, _("error syncing %s"), quoteaf (file));
 155           ret = false;
 156         }
 157     }
 158
 159   if (close (fd) < 0)
 160     {
 161       error (0, errno, _("failed to close %s"), quoteaf (file));
 162       ret = false;
 163     }
 164
 165   return ret;
 166 }
 167
 168 int
 169 main (int argc, char **argv)
 170 {
 171   int c;
 172   bool args_specified;
 173   bool arg_data = false, arg_file_system = false;
 174   enum sync_mode mode;
 175   bool ok = true;
 176
 177   initialize_main (&argc, &argv);
 178   set_program_name (argv[0]);
 179   setlocale (LC_ALL, "");
 180   bindtextdomain (PACKAGE, LOCALEDIR);
 181   textdomain (PACKAGE);
 182
 183   atexit (close_stdout);
 184
 185   while ((c = getopt_long (argc, argv, "df", long_options, nullptr))
 186          != -1)
 187     {
 188       switch (c)
 189         {
 190         case 'd':
 191           arg_data = true;
 192           break;
 193
 194         case 'f':
 195           arg_file_system = true;
 196           break;
 197
 198         case_GETOPT_HELP_CHAR;
 199
 200         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 201
 202         default:
 203           usage (EXIT_FAILURE);
 204         }
 205     }
 206
 207   args_specified = optind < argc;
 208
 209   if (arg_data && arg_file_system)
 210     error (EXIT_FAILURE, 0,
 211            _("cannot specify both --data and --file-system"));
 212
 213   if (!args_specified && arg_data)
 214     error (EXIT_FAILURE, 0, _("--data needs at least one argument"));
 215
 216   if (! args_specified || (arg_file_system && ! HAVE_SYNCFS))
 217     mode = MODE_SYNC;
 218   else if (arg_file_system)
 219     mode = MODE_FILE_SYSTEM;
 220   else if (! arg_data)
 221     mode = MODE_FILE;
 222   else
 223     mode = MODE_DATA;
 224
 225   if (mode == MODE_SYNC)
 226     sync ();
 227   else
 228     {
 229       for (; optind < argc; optind++)
 230         ok &= sync_arg (mode, argv[optind]);
 231     }
 232
 233   return ok ? EXIT_SUCCESS : EXIT_FAILURE;
 234 }